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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Wed, 25 Nov 2020 03:44:58 +0900
Message-ID: <CAK7LNASatgWjE7MGe-cqU135tKD_Tt31Rouw-HSz6LYrN5hyuw@mail.gmail.com>
Subject: Re: [PATCH v3] Kbuild: do not emit debug info for assembly with LLVM_IAS=1
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-toolchains@vger.kernel.org,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Fangrui Song <maskray@google.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Dmitry Golovin <dima@golovin.in>,
        Alistair Delva <adelva@google.com>,
        "# 3.4.x" <stable@vger.kernel.org>, Jian Cai <jiancai@google.com>
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On Tue, Nov 24, 2020 at 3:42 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> Hi Masahiro,
> I would appreciate any feedback you have on this patch.
>

Applied to linux-kbuild. Thanks.


> On Fri, Nov 20, 2020 at 3:58 PM Jian Cai <jiancai@google.com> wrote:
> >
> > I also verified that with this patch Chrome OS devices booted with eith=
er GNU assembler or LLVM's integrated assembler. With this patch, IAS no lo=
nger produces extra warnings compared to GNU as on Chrome OS and would remo=
ve the last blocker of enabling IAS on it.
> >
> > Tested-by: Jian Cai <jiancai@google.com> # Compile-tested on mainline (=
with defconfig) and boot-tested on ChromeOS (with olddefconfig).
> >
> >
> > On Mon, Nov 16, 2020 at 3:41 PM 'Nick Desaulniers' via Clang Built Linu=
x <clang-built-linux@googlegroups.com> wrote:
> >>
> >> Hi Masahiro, have you had time to review v3 of this patch?
> >>
> >> On Mon, Nov 9, 2020 at 10:35 AM Nick Desaulniers
> >> <ndesaulniers@google.com> wrote:
> >> >
> >> > Clang's integrated assembler produces the warning for assembly files=
:
> >> >
> >> > warning: DWARF2 only supports one section per compilation unit
> >> >
> >> > If -Wa,-gdwarf-* is unspecified, then debug info is not emitted for
> >> > assembly sources (it is still emitted for C sources).  This will be
> >> > re-enabled for newer DWARF versions in a follow up patch.
> >> >
> >> > Enables defconfig+CONFIG_DEBUG_INFO to build cleanly with
> >> > LLVM=3D1 LLVM_IAS=3D1 for x86_64 and arm64.
> >> >
> >> > Cc: <stable@vger.kernel.org>
> >> > Link: https://github.com/ClangBuiltLinux/linux/issues/716
> >> > Reported-by: Dmitry Golovin <dima@golovin.in>
> >> > Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> >> > Suggested-by: Dmitry Golovin <dima@golovin.in>
> >> > Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
> >> > Suggested-by: Sedat Dilek <sedat.dilek@gmail.com>
> >> > Reviewed-by: Fangrui Song <maskray@google.com>
> >> > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> >> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> >> > ---
> >> >  Makefile | 2 ++
> >> >  1 file changed, 2 insertions(+)
> >> >
> >> > diff --git a/Makefile b/Makefile
> >> > index f353886dbf44..7e899d356902 100644
> >> > --- a/Makefile
> >> > +++ b/Makefile
> >> > @@ -826,7 +826,9 @@ else
> >> >  DEBUG_CFLAGS   +=3D -g
> >> >  endif
> >> >
> >> > +ifneq ($(LLVM_IAS),1)
> >> >  KBUILD_AFLAGS  +=3D -Wa,-gdwarf-2
> >> > +endif
> >> >
> >> >  ifdef CONFIG_DEBUG_INFO_DWARF4
> >> >  DEBUG_CFLAGS   +=3D -gdwarf-4
> >> > --
> >> > 2.29.2.222.g5d2a92d10f8-goog
> >> >
> >>
> >>
> >> --
> >> Thanks,
> >> ~Nick Desaulniers
> >>
> >> --
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LBA%40mail.gmail.com.
>
>
>
> --
> Thanks,
> ~Nick Desaulniers


--=20
Best Regards
Masahiro Yamada